If you have enough obsidian you could try to put a three layers insulation around the volcano. Obsidian is not a good insulator but it will not melt with lava. The first layer would be at 1500°C then the second would be 800°C or so and then the last should not be too high and should be cool enough to not impact your base too much.
Edit : Or you could build a single obsidian insulation layer and create vacuum between the insulation and a regular tile wall.
Anyway, when dealing with regular volcanoes, obsidian is your best friend.

I find it fun to handle the very high moral requirement of a dupe or two. I usually have a dupe trained in mech engineer early on. And to counter that I try to get the sunny disposition to counter the effect of bad morale.
But it's just me. I like to give my dupes the best life they can get so everyone gets stuffed berry

@GemeinerJack : The build that @Lawmower Man showercased might be modifiable to suit your use case.
If you space pipes by one tile and put bridges so pipe 1 gets pipe 2 input at first instead of pipe 1 gets pipe 3 input, you will only need to overfill the start and then the system will run as you expect I think.

I'd go with that sentence. You literally said that you learn nothing by making an analogy between a 7v1 RTS game and choosing a seed in ONI. I'm not saying it. You are. Hence my post. Because it's not true at all. We all learn differently and analogies like that are generalizations... Generalizations leads to dead-end discussions. Or worse.
When playing Pokemon -> You gather pokemons -> You build a team -> You train your pokemons -> You fight other trainers. Is that the same kind of game ? Are we all playing Starcraft2 and ONI thinking those are unique games when in fact we all play Pokemon ?
You can't make those vague analogies because then why have RTS type of game and Simulation/Survival type of game if they are the same ? That's why there are categories. And you can't compare the learning processus of a RTS game and a simulation game.
Also you said you can't learn anything when it's simple.
I'm not. I'm just explaining my point and disagree with yours. Having a different opinion is not being bitter.

The screen showing only one input pipe is normal. That's why he needs 10 times that screen and it becomes absurd in size.
I think he's trying to make a lot of liquid O2 for rockets. But only him can confirm.

I looked at it the first and thought "Meh seems pretty useless". But when looking at it again I mut say it's very simple and very usefull for rockets where you don't want to have liquids sitting in pipes. Nice PoC @fox_kirya

I really think that the kind of analogy are not good at all.
You can't compare a RTS and ONI. Because... Well... It's not the same type of game.
RTS are pretty straight forward -> Gather resources -> Build base -> Train troops -> Kill the enemy.
To "win" a game in ONI you have to understand what you're doing and manipulate a great variety of machines that works differently. Even plants are machines of some sort that have special needs. You can't say that by choosing what geysers are in the map you can't learn anything. The game is already a challenge when you start.
Yes. When you have 800 hours in ONI and launched hundreds of rockets then you won't have a challenge when choosing a seed with lots of cool slush geysers. But you can still improve your designs, try to build different contraptions or/and use a different way to play the game.
You really should not make a judgment on people that use seeds. Respect others opinions and their way to play a game.
(And just because I thought of this little quote even though it has no link : Opinions are like *******s. Everybody has one.)